Abstract

OBJECTIVE:

Non-alcoholic fatty liver disease (NAFLD) is an important co-morbidity associated with obesity and a precursor to steatohepatitis. However, the contributions of gestational and early life influences on development of NAFLD and NASH remain poorly appreciated.

METHODS:

Two independent studies were performed to examine whether maternal over-nutrition via exposure to high fat diet (HFD) leads to exacerbated hepatic responses to post-natal HFD and methionine choline deficient (MCD) diets in the offspring. Offspring of both control diet- and HFD-fed dams were weaned onto control and HFD, creating four groups.

RESULTS:

When compared to their control diet-fed littermates, offspring of HF-dams weaned onto HFD gained greater body weight; had increased relative liver weight and showed hepatic steatosis and inflammation. Similarly, this group revealed significantly greater immune response and pro-fibrogenic gene expression via RNA-seq. In parallel, 7-8 week old offspring were challenged with either control or MCD diets for 3 weeks. Responses to MCD diets were also exacerbated due to maternal HFD as seen by gene expression of classical pro-fibrogenic genes. Quantitative genome-scale DNA methylation analysis of over 1 million CpGs showed persistent epigenetic changes in key genes in tissue development and metabolism (Fgf21, Ppargc1β) with maternal HFD and in cell adhesion and communication (VWF, Ephb2) in the combination of maternal HFD and offspring MCD diets. Maternal HFD also influenced gut microbiome profiles in offspring leading to a decrease in α-diversity. Linear regression analysis revealed association between serum ALT levels and Coprococcus, Coriobacteriacae, Helicobacterioceae and Allobaculum.

DNA methylation changes in livers of offspring from lean and obese dams challenged with MCD diet.

Genome-scale DNA methylation was assessed using RRBS. (A) Percent frequency distribution of methylation status of informative promoters (TSS), promoters containing CGI (TSS_CGI), all CGIs, in offspring from lean and HFD dams challenged with control or MCD diet. Methylation status of features is binned into 5 categories (0%–20%, 20%–40%, and so on). (B) Genomic localization of differentially methylated regions (DMRs). (C) Δme (difference in average methylation between groups) for each DMR showing both hypo and hypermethylated regions. See full list in Supplementary tables. Each group was compared against CC offspring.

Scatter plots of average methylation of DMRs showing altered methylation with (A) maternal HFD, or (B) the combination of maternal HFD and offspring MCD diet are presented along with annotation of key genes. (C-D) Enrichment of GO biological process terms of DMRs in proximity of the genes in (C) CC vs HC and (D) CC vs H-MCD comparisons. Maternal HFD influences methylation of regions proximal to (E)Ppargc1β and Fgf21. The combination of maternal HFD and offspring MCD diet feeding influences methylation of regions close to Ephb2 and Vwf. Average methylation of the DMR is depicted on the histograms in the two lower tracks.